Circuit controller for railway switch machines



Aug. 6, 1968 R. w. KUGLER ETAL 3,396,270

CIRCUIT CONTROLLER FOR RAILWAY SWITCH MACHINES 4 Sheets-Sheet 2 Filed Dec. 25, 1965 CIRCUIT CONTROLLER FOR RAILWAY SWITCH MACHINES Aug. 6, 1968 R. w. KUGLER ET AL 4 Sheets-Sheet 3 Filed Dec.

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6J L LSZ-j 7 150915 rwoemm 4 Sheets-Sheet 4 Aug. 6, 1968 R. w. KUGLER ETAL CIRCUIT CONTROLLER FOR RAILWAY SWITCH MACHINES Filed Dec. 23, 1965 m MQ E NRR Qmw @m a Qmm 1 Q \I/Q @m 1 Q. @IWWW wj v rmm Q g m W m zmw Eu 5 I n! d United States Patent 3,396,270 CIRCUIT CONTROLLER FOR RAILWAY SWITCH MACHINES Ralph W. Kugler, Brookline, and Robert A. Wenston, Pittsburgh, Pa., assignors to Westinghouse Air Brake Company, Swissvale, Pa., a corporation of Pennsylvania Filed Dec. 23, 1965, Ser. No. 515,875 19 Claims. (Cl. 246218) ABSTRACT OF THE DISCLOSURE A circuit controller for railway switch machines having a recessed point detector bar and a notched lock rod connected to the switch points; a slide bar having a looking dog for engaging the notched lock rod and locking the switch points in either of their extreme positions; a mechanical coupling assemblage including two linkages each having a crank with a roller and pin; each linkage connected to and closing respective contacts of an electrical contact assembly when its respective roller and pin simultaneously communicate with the recessed point detector bar and notched lock rod for ensuring that the switch points are properly positioned and locked in their extreme position.

Our invention relates to a railway switch machine circuit controller and, more specifically, to a new and improved circuit controller arrangement which performs a corresponding check between the point detector rod and the lock rod to ensure that the switch points of the railway switch are properly positioned and locked in the selected one of their two extreme positions.

A railway switch machine generally comprises an electrical motor controlled from a remote point to move the switch points of the switch machine between their two extreme positions, namely, reverse and normal positions, and thereafter locking them in the extreme position to which they are moved. Normally, such switch machines also include a circuit controller which is operated in part by a slide bar and a point detector mechanism for controlling suitable electrical indication and motor control contacts which indicate when the switch points are properly positioned and locked in, for example, the reverse position and which establish the appropriate motor circuit whereby the switch machine may be moved to its normal position when desired, and vice-versa. In previous switch machines, the circuit controller normally involves a myriad of intricate and complex electrical and mechanical elements cooperatively interrelated for establishing the appropriate circuits for the driving motor as well as for the indication signals when the switch points assumed and were locked in proper association with the stock rails. For example, the contact means for controlling the circuits for the drive motor consisted of two pairs of horizontally disposed contact fingers which cooperated with associated metallic contact ring segments carried by a rectangular cross-sectional horizontally disposed camshaft. Each of these metallic contact segments are normally carried by associated insulating bushings which include a square opening for slidably being received and suitably disposed on the camshaft. The camshaft is adapted to be journaled in a pair of trunnions for oscillatory movement about its longitudinal axis. A gear wheel is fixedly secured on the camshaft and meshes with the teeth of a pinion gear which, in turn, cooperates with a rack carried by a lock box on the slide bar thereby causing oscillatory movement of the camshaft in response to the longitudinal movements of the slide bar. The contact means used to control the indication circuits normally consists of two pairs of horizontally disposed contact fingers. Each pair Patented Aug. 6, 1968 of contact fingers is interconnected by an insulating bridge for simultaneous movement therewith and also is normally biased in a downward direction by its own resiliency. The interconnecting bridges include rollers which cooperate with cams having notches therein for controlling the position of the contact finger. The cams cooperate with the hubs of the camshaft gear wheel for rotation therewith. A plurality of washers, bushings, drive pins and radial slots are suitably disposed and so arranged to cause each pair of contact fingers to engage an upper stationary contact when the rollers engage the surface of the cams and to cause each pair of contact fingers to engage an indication signal contact when the rollers are aligned with the notched portions of the cams. Further, in order to control the indication contact fingers in accordance with the position of the switch points the camshaft is also required to accommodate a U-shaped contact operating member and a pair of operating levers which cooperate with a pair of point detector levers through suitable operating rods. The U-shaped contact member is provided with a pair of cammed surfaces formed on a first pair of arms. The U-shaped contact operating member also includes a second pair of arms with each arm having alhxed thereto, by means of a pin and a snap-ring, a driving block. The driving blocks slidably engage and cooperate with projecting jaws of the two operating levers for operational engagement therewith. Further, the two operating levers are provided With depending arms which pivotally cooperate with one end of the previously mentioned operating rods. The other end of the operating rods is pivotally connected to the point detector levers which sense, by means of rollers, the position of the switch point detector bar which is representative of the position of the switch points.

While such previous forms of circuit controllers for switch machines have operated satisfactorily in the past there are several features which are objectionable. For example, the problem of maintaining and field servicing is not only time consuming but also, in many cases, difficult due to the complexity of such a circuit controller arrangement. Further, the intricacy of such circuit controllers not only substantially increases the initial purchase cost of the railway switch machines but also proportionally increases the maintainence cost of the switch machine. For example, the fabricating costs of the intricate and numerous elements of the circuit controller is relatively high. Similarly, the electrical and mechanical wear of the numerous parts requires not only frequent replacements but also repeated adjustments which results in a high maintainence cost. Further, during periods of routine maintainence, it was virtually impossible to readily determine whether the motor and indication contacts were either opened or closed, that is, in a normal or reverse position, since the contact points are usually obscured from visual observation. Further, these prior art types of rotary cam operated electrical contacts involve excessive motion so that increased wear and decreased life are inherently common characteristics of such circuit controllers.

Accordingly, it is an object of our invention to provide a new and improved circuit controller for railway switch machines.

Another object of our invention is to provide a novel and improved circuit controller which performs a correspondence check of the lock rod and point detector bar to ensure that the switch points are locked and occupy their proper positions relative to the stock rails in either of their extreme positions.

A further object of our invention is to provide a unique circuit controller which will restrict trafiic movement over the switch by opening the appropriate indication contacts in the event a switch locked in either of its extremev positions is trailed, and which also restricts traffic movement over a switch by preventing closure of clear indication contacts when the switch points either fail to assume and lock in their normal or reverse positions for any reason.

A still further object of our invention is to provide a unique circuit controller wherein the position of the electrical indication and control contacts are readily ob servable by an individual so that the position and condition of the switch machine may be immediately determined upon inspection.

Yet another object of our invention is to provide a unique circuit controller which utilizes a minimum number of elements thereby appreciably reducing the wear and increasin the life of a railway switch machine.

Still yet a further object of our invention is to provide an improved circuit controller for switch machines which is simple in design, economical to manufacture, etficient in operation, and endurable in use.

In accordance with the present invention, our unique circuit controller includes an electrical contact assembly having a plurality of fixed U-shaped spring contacts and a plurality of movable knife-blade bridging contacts associated therewith. The fixed spring contacts are arranged in grouped pairs and are suitably interconnected to the motor control, the indication shunt and the signal indication circuits of a railway switch machine. The movable bridging contacts are suitably arranged in two groups with each group being carried by a movable block which is slidably movably between a first and a second position for opening or closin selected pairs of the fixed spring contacts. The relative position of each movable block and its bridging contacts is separately and independently controlled by means of a mechanical coupling assemblage including a first and a second articulated linkage. Each articulated linkage includes a pivoted crank having a roller for cooperating with a point detector bar and/or its recess and a lock pin for cooperating with one or two suitable notches formed in a lock rod. Each pivoted crank is provided with a helical spring for suitably biasing each pivoted crank in cooperative association with the point detector bar and the lock rod. Each linkage also includes a turnbuckle and a pair of eye bolts. The free end of one eye bolt is suitably pivotally connected to its associated pivoted crank while the free end of the other eye bolt is connected by a pivot pin to one arm of a first bell crank of which is pivotally supported by means of a pivoted shaft. The other arm of each of the first bell cranks is suitably connected to a separate movable block by means of a push rod. Each linkage also includes a cam follower having fixed at one end a suitable roller for cooperating with a wedge-shaped cam member carried by a slide bar. The other end of each cam follower is pivotally connected to one arm of a second bell crank each of which is securely fastened to one end of its associated pivoted shaft. The other arm of each of the second bell cranks is suitably spring biased to constantly urge its bell crank and, in turn, its associated cam follower toward the slide bar cam member so that the rollers frictionally engage the respective surfaces of the wedgeshaped cam. Securely fastened to the other end of each of the pivoted shafts is a kicker arm having an adjustable stud which is cooperatively associated with the pivot pin provided in the one arm of each of the first bell cranks. When the switch points are suitably positioned and locked in their normal position, the first linkage is so arranged that its roller engages the recess of the point detector bar and its lock pin engages one of the notches of the lock rod so that the movable block and its group of movable contacts assume the first position wherein the normal indication contacts are closed and the normal motor control and shunting contacts are opened. Conversely, under this condition, the roller of the second linkage engages the largre peripheral portion of the point detector bar and its lock pin engages the outer extremity of the lock rod so that its associated movable block and its group of movable contacts assume the second position wherein the reverse motor control and shunting contacts are closed and the reverse indication contacts are opened. When it is desirable to move the switch points to their reverse position, the switch machine experiences an initial unlocking stroke wherein the slide bar moves to retract a locking dog from a locking notch situated in the bottom in the bottom of the lock rod. The movement of the slide bar causes the wedge-shaped cam member to move therewith so that the associated cam followers are moved apart. The movement of the cam follower associated with the first linkage causes its second bell crank and, in turn, its kicker arm to rotate about the pivoted shaft so that the stud which is in engagement with the bell crank pin causes the first bell crank to rotate therewith. The rotational movement of the first bell crank is transmitted to the movable block through its push rod so that the movable block assumes its second position. The transposition of the movable block results in the interruption of the normal indication contacts and the closure of the normal motor control and the shunt indication contacts. The rotational movement also causes the roller to be withdrawn from the recess of the point detector bar and the lock pin to be retracted from the notch on the lock rod. During this unlocking stroke, no appreciable change occurs to the second linkage other than the rotational dislacement of the second bell crank and its kicker arm caused by the movement of its cam follower. Accordingly, the circuit controller assumes a mid-stroke position and the switch points are free to be moved from their normal to their reverse position during the following movement which may be termed, the operating stroke of the switch machine. Upon completion of the operating stroke, the final or locking stroke commences in which the slide bar is moved to cause the locking dog to enter and engage an appropriate notch located in the bottom of the lock rod. The movement of the slide bar also causes the wedge-shaped cam member along with the cam followers, the second bell cranks and the kicker arms to be restored to their original positions. Upon completion of the locking stroke, the second linkage is 50 arranged that its roller enters the recess of the point detector bar and its locking pins enters the other notch of the lock rod. The entrance of the roller and locking pin causes rotation displacement of the crank which, in turn, is transmitted to the second bell crank through the turnbuckle link. The rotational displacement of the second bell crank causes the push rod of the second linkage to move its movable block to its first position. Accordingly, the movable contacts interrupt the reverse motor control and shunt indication contacts and close the reverse indication contacts thereby signifying that the switch points are properly positioned and locked in their reverse position. Since the roller of the first linkage engages the larger peripheral portion of the point detector bar and its locking pin engages the inner extremity of the lock trod, the movable block and its contacts, remain in their second position to which they have been previously moved. Obviously, the switch machine operates in the reverse manner when it is desirable to move the switch points from their reverse to their normal position.

We shall describe one form of a circuit controller arrangement embodying our invention, and shall then point out the novel features and advantages thereof in the claims.

The above objects and other attedant features and advantages of this invention will become more fully evident from the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a top plan view of a railway switch having switch points operated by a switch operating machine including a circuit controller arrangement embodying our invention.

FIG. 2 is a partial top plan view on an enlarged scale of the switch machine shown in FIG. 1 with the cover of the machine being removed to better illustrate the construction and arrangement of the operating, locking, point detecting, and circuit controller arrangement embodying our invention.

FIG. 3 is a sectional view taken approximately along line III-III of FIG. 2.

FIG. 4 is a schematic diagram illustrating the midstroke position of the operating, locking, point detecting, and circuit controller arrangement embodying the present invention.

FIG. 5 is a schematic diagram illustrating the reverse position of the operating, locking, point detecting, and circuit controller arrangement embodying the present invention.

Referring to the drawings, wherein like parts are indicated by like reference numerals in each figure, and in particular to FIG. 1, the reference character A designates a railway switch comprising two stock or fixed rails 1a and 1b and two movable switch points 2a and 2b. The fixed rails 1a and 1b are normally placed on tie plates 3 and thereafter are secured in the usual and well known manner to the cross ties 4. The movable points 2a and 2b are fastened together for simultaneous movement by a head rod 5 and a front rod 6. The switch may be defined as occupying its normal position when the movable point 2a engages the fixed rail 1:: while the movable point 2b is spaced from the fixed rail 1b as illustrated in FIG. 1. Conversely, the switch may be defined as occupying its reverse position when the movable point 2b engages the fixed rail 1b while the movable point 2a is spaced from the fixed rail 1a.

Cooperating with and suitably secured to cross ties 4, adjacent the outer side of the fixed rail in, is a switch machine or operating mechanism B comprising a suitable casing 7 divided into three compartments with each compartment being provided with a separate removable cover, namely, 7a, 7b and 70. These three compartments of the switch operating mechanism consists of a motor compartment covered by cover 7a, a gear reduction compartment covered by cover 7b, and a circuit controller compartment covered by a cover 7c. The switch points are interconnected with the switch operating mechanism B and are moved between their normal and reverse positions by means of a throw rod 5a which is connected to the head rod 5 by means of the usual switch basket 5b. The throw bar 5a passes under the movable switch point 2a and the fixed rail 1a and is connected at its free end with a switch operating bar 8 which is longitudinally movable within suitable bearings associated with the reduction gear compartment of the railway switch machine B. An adjustable lock connecting rod 6a and an adjustable point detector rod 6b are fixedly secured by suitable means to the front rod 6 and extend beneath the fixed rail 1a to the circuit controller compartment of the railway switch operating mechanism B. The lock connecting rod 6a is connected at its free end to a lock rod 9 which is suitably guided by rollers, not characterized, and slidably received within the circuit controller compartment of the railway switch machine B. The free end of the connecting rod 6b is connected to a point detector bar 10 which is journaled and slidably received within the circuit controller compartment which will be described in further detail hereinafter.

Referring now to FIGS. 2 and 3, the switch machine is again characterized by the letter B, however, the covers of the switch machine are shown removed from FIG. 2 in order to illustrate in greater detail the switch operating, locking, point detecting, and the circuit controller mechanism. During normal operations, the movable points of the switch will be moved between their normal and reverse positions upon energization of the drive motor which cooperates with the switch operating and locking mechanisms through crank 11. The motor supplies the primary power for operating the switch machine through a suitable gear train, not shown, through a worm gear afiixed to crankshaft 11a. The crankshaft 11a is journaled in suitable bearing means, not shown, so that the worm gear, which forms part of the gear train, rotates the crankshaft 11a about its vertical axis. The free arm of crank 11 is provided with a suitable depending pin which carries a roller 11b. The roller 11b cooperates with a longitudinal cam slot 8a provided in crossarm 8b formed integrally with the operating rod 8. The crank 11 also cooperates with a slide bar 12 which is disposed lengthwise in the bottom of easing 7. The roller 11b engages an arcuate slot 12a formed in a crossarm 12b for laterally moving slide bar 12 between two extreme positions. The slide bar 12 is provided at its extreme left-hand end with a bifurcated section 120 which cooperates with guide member 13 for ensuring the lateral motion of the slide bar 12. The slide bar 12 also includes on its upper face an integrally formed wedge-shaped cam member 12d and locking dog 12s the function of each of which will be described in more detail hereinafter.

As previously mentioned, the movable switch points 2:; and 2b are interconnected by means of connecting rod 6a to the lock rod 9 situated within the circuit controller compartment. The lock rod 9 is of substantially standard construction and consists of two rectangular cross-sectional bars arranged in side-by-side relationship. Each bar is formed with a pair of notches in its lower edge. The bars are so proportioned and adjusted that the pair of notches of one bar are coincident and in alignment with the pair of notches of the other bar so that two thru notches 9a and 9b are formed by the lock bars. The two notches 9a and 9b formed in the lock rod are spaced apart a distance which is substantially equal to the switch stroke so one notch coincides with each extreme position of the switch points, and furthermore each notch is of a suitable width to accommodate the locking dog 12c whereby the switch points are locked in the extreme position to which they have been moved. Each locking bar of the locking rod 9 also contains an upper notch, namely, and 9d, the operation of which will be described more fully hereinafter.

As previously mentioned, the front rod 6, which interconnects the two movable points 2a and 2b, is coupled to the point detector bar 10 through the connecting rod 6b. The point detector bar 10 which is also slidably received within the circuit controller compartment ensures that the movable switch points are properly positioned in relation to the fixed rails when the switch assumes either of its extreme positions. The point detector bar 10 which is of circular cross-section includes a reduced elongated peripheral portion or recess 10a enclosed within the circuit controller compartment. The point detector bar and the lock rod are adapted to co-act with elements of a circuit controller which will now be described.

The circuit controller includes an electrical contact assembly and an associated mechanical coupling assemblage which are removable as a complete unit. The contact assembly generally shown by character 16 comprises a rectangular framework having a pair of slotted end guide members 18:: and 18b, a slotted central guide memher 180, and a pair of L-shaped members 19a and 19b suitably secured to base plate or supporting frame 17 which is conveniently mounted in the circuit controller compartment. A pair of terminal boards 20a and 20b carrying a plurality of U-shaped spring contacts 29-40 and 41-48 is suitably secured to the Lshaped members 19:: and 19b, respectively. These fixed or stationary U-shaped spring contacts are electrically connected or wired to a standard terminal board which is suitably interconnected to a suitable drive motor, for example, a split field DC. motor, and to a plurality of signal repeater relays. Accordingly, the U-shaped spring contacts 29-48 are electrically interconnected with the motor control, and the indication signal and the indication shunting circuits of 7 the railway switch machine. Cooperatively associated with the fixed U-shaped spring contacts are a plurality of movable silver-tungsten contacts 52, 52a, 53b, 54a, 54b, 55a, 55b, 56a, 56b and 57 in the form of knife-blade bridging contacts which are selectively moved in and out of electrical contact with a selected pair of the fixed contacts 29-48. The bridging contacts are moved into and out of engagement with their associated pair of fixed spring contacts by means of slidable metallic contact blocks 58a and 58b having mounted thereon suitable terminal boards 59a and 59b which electrically insulate the bridging contacts. Each contact block includes a guide pin 51, one of which is shown in FIG. 3, fixed to each end for communicating with suitable slotted guideways provided in the two end and the center guide members 18a, 18b and 180. The electrical contacts are arranged in two groups, with the electrical condition of each group being independently and separately controlled by the specific position assumed by its associated contact block. The first group consists of fixed contacts 29-34 and 41-44 and movable contacts 52, 53a, 53b, 54a and 54b. Contacts 29 and 30 are adapted to be engaged and closed by movable contact 52 which functions to short-circuit the reverse signal control relay thereby eliminating the possibility of stray currents or crosses on the external leads from energizing the relay improperly and causing an improper signal indication. Contacts 31 and 32 are adapted to be engaged and closed by knife blade 53a, and contacts 33 and 34 are engaged and closed by knife blade contact 54a for providing a double make and break contact arrangement for the reverse motor control circuit. Contacts 41 and 42 areadapted to be engaged and closed by knife blade 53b, and contacts 43 and 44 are adapted to be engaged and closed by knife blade 54b for providing a double make and break contact arrangement for the reverse signal indication circuit. The second group of electrical contacts consists of fixed contacts 49 and 45-48 and movable contacts 55a, 55b, 56a, Sfib and 57. Contacts 39 and are adapted to be engaged and closed by knife blade 57 which functions as a short-circuiting means for preventing stray currents or crosses on the external wires from energizing the normal signal indication relay improperly thereby eliminating the possibility of improper signal indications. Contacts 35 and 36 are adapted to be engaged and closed by knife blade 55a, and contacts 37 and 38 are adapted to be engaged and closed by knife blade contact 5611 for providing a double make and break contact arrangement for the normal motor control circuit. Fixed contacts and 46 are adapted to be engaged and closed by knife blade contact b, and fixed contacts'47 and 48 are adapted to be engaged and closed by movable contact 55b for providing a double make and break contact arrangement for the normal signal indication circuit. As will readily be noted, the movable contacts and the fixed contacts are arranged in positional agreement with the movable switch points 2a and 2b as illustrated in FIG. 1.

As previously mentioned, the point detector bar 14 is utilized to indicate the relative position of the movable switch points while the lock rod 9 assures proper locking of the movable switch points in the extreme position to which the switch points have been moved. In order to transfer the existing position of the movable switch points 2a and 2b, which is characterized by the position of the point detector bar 10 and the lock rod 9, to the circuit controller contact assembly for opening and closing the appropriate electrical control and indication circuits in agreement therewith, a unique mechanical coupling assemblage is employed. The mechanical circuit controller coupling assemblage, generally shown by character 60, includes two substantially identical articulated linkages which separately and independently control the two groups of the electrical contacts. Each of these linkages includes a lever or crank, namely, cranks 61a and 61b pivotally mounted on upstanding pins 62a and 62b suitably secured to the base plate or frame 17. The cranks 61a and 61b are provided at their outer ends or arms with rollers 63a and 63b, respectively, which cooperate with the point detector bar 10 and its recess or reduced portion 10a. Further, each of the point detector cranks includes an intermediate arm having locking pins 64a and 64b affixed to the end removed from pivot pins 62a and 62b for cooperating with notches 9c and 9d of the lock bar 9. Each crank also includes a tension spring 65a and 65b, respectively, connected at one end to the inner arm of cranks 61a and 61b and connected at the other end to lugs 65c and 65d which are suitably secured to frame 17. Tension spring 65a constantly biases the crank 61a in a clockwise direction while the tension spring 65b constantly biases the crank 61b in a counterclockwise direction. The extreme end of each of the inner arms of the cranks 61a and 61b is pivotally secured to eye bolts 66a and 66b by means of screws 67a and 67b, respectively. The threaded end of each eye bolt is screwed into one end of turnbuckles 68a and 68b, respectively. The other end of turnbuckles 68a and 68b threadably engage eye bolts 69a and 69b, respectively. The eye portion of each of the bolts 69a and 69b is, in turn, pivotally connected to bell cranks 70a and 70b by means of pin stops 71a and 71b which extend slightly above the upper surface of the bell cranks. The turnbuckles not only cooperatively interconnect the two eye bolts of each linkage but also provide means for suitably and individually adjusting the length of each linkage. The bell cranks 70a and 70b are pivotally supported on pivot shafts 72a and 72b and are free to rotate relative thereto. Each of the respective linkages is provided with an L-shaped push or operating rod 73a and 73b for interconnecting the movable contact blocks 58a and 58b with its associated bell crank. The longer leg of each push rod passes through suitable apertures provided in channel member 19b and is suitably fastened to its respective contact block, for example, by an adjustable threaded connection. The shorter leg of each push rod extends upwardly through and is pivotally connected at points 74a and 74b in the respective driven arm of bell cranks 70a and 70b. A pair of hell cranks 75a and 75b are disposed on the underside of the base plate or frame 17 and are securely fixed, by a tapered pin connection, to the lower end of shafts 72a and 72b, respectively. The upper end of each of the pivoted shafts which extends above the frame 17 has suitably keyed thereto a kicker arm, namely, 76a and 76b. The kicker arms 76a and 76b include adjustable studs 77a and 77b along with nuts 77c and 77d for locking the studs. The free end of studs 77a and 77b are in rotational alignment with stop pins 71a and 71b for limiting the angular rotation or displacement of bell cranks 70a and 70b, about shafts 72a and 72b, as will be more fully described hereinafter. Suitable tension springs 78a and 78b are connected at one end to the extreme portion of one arm of bell cranks 75a and 75b, respectively, and at the other end to lugs 79a and 79b on frame 17. Spring 78a constantly biases the bell crank 75a and kicker arm 76:: in a counterclockwise direction While spring 78b constantly biases bell crank 75b and kicker arm 76b in a clockwise direction. The other arm of each of the bell cranks 75a and 75b is bifurcated and is adapted to pivotally accommodate one end of cam follower, namely, 80a and 80b, respectively. The other end of each of the cam followers 80a and 80b is provided with suitable rollers 81a and 8112 which cooperately en gage and travel on the respective surfaces of the Wedgeshaped cam 12b of slide bar 12. The cam followers are guidingly carried by suitable guide blocks 82a and 82b which are securely fastened by bolts, not characterized, to the under side of frame 17. The guide blocks are arranged to limit the movement of the cam follower along their longitudinal axis.

The actual operating and locking function of the switch points although controlled by the crank 11 is in reality performed by the operating rod 8 and the slide bar 12.

The operating rod and the slide bar operate in a particular sequence for moving the switch points between their extreme positions, namely, the switch machine follows the steps of unlocking, operating, and locking, in moving the switch points from one extreme position to the other. Further, in the interest of safety, it is necessary that the switch points be properly positioned and looked in the extreme position to which they have been moved prior to permitting clear signals, which govern trafiic over the switch, to be established. This proper locking and positioning function is performed by the circuit controller which is operated jointly by the slide bar, the lock rod, and the point detector bar. For example, the rollers of the cam followers 80a and 80b which cooperate with the wedge-shaped cam 12]) of the slide bar allow the pins 64a and 64b to check with notches 9c and 9d of the lock rod 9 for ensuring proper locking of the switch points while rollers 63a and 63b check with point detector bar 10 and its recess for ensuring proper positioning of the switch points. This locking and positioning information is then mechanically transferred by the separate articulated linkages to the two groups of electrical contacts which appropriately establish circuits in agreement with the condition of the switch points. As will become evident hereinafter, the circuit controller not only ensures that the switch machine properly completes its operating and locking function but also constantly checks that the switch points remain properly positioned and locked in the extreme position to which they have been moved.

Now assuming that all the necessary adjustments have been made and that the railway switch is operating properly, reference is made to FIG. 2 which illustrates the various elements of the switch machine in their normal position with the movable switch point 2a engaging the fixed rail 1a as shown in FIG. 1. Under this condition, the crank 11 is located in its extreme counterclockwise position while the operating bar 8 assumes its uppermost position and the slide bar 12 assumes its extreme left-hand position. When the slide bar 12 is in this extreme lefthand position and the locking dog 12e is in engagement with notch 9a, the switch points are properly locked. Further, since the point detector bar is properly positioned, the point detector roller 63a is opposite the small diameter portion or recess 10a of the detector bar and the depending or locking pin 64a is within notch 9c of the lock rod so that the movable contact block 58a assumes a position wherein movable contacts 55b and 56b engage and close the stationary contacts 45-46 and 47- 48. Conversely, the point detector roller 63b engages the larger diameter portion of the point detector bar 16 and the depending or locking pin 64b is in abutment with the outer extremity of lock rod 9 so that the movable block 59b assumes a position wherein movable contacts 52, 53a and 54a engage and close the stationary contacts 29-30, 31-32 and 33-34, respectively. Accordingly, when the railway switch is properly positioned and locked in its normal position, the circuit controller is arranged and so adjusted that the normal indication contacts 45-48, the reverse signal shunt contacts 29 and 30, and the reverse motor control contacts 31-34 are closed, and the reverse indication contacts 41-44, the normal signal shunt contacts 39 and 40, and the normal motor control contacts 35-38 are opened.

Assuming now that it is desirable to operate the railway switch from its normal position to its reverse position wherein switch point 2b engages fixed rail 1b, it is merely necessary to energize the reverse motor circuit to begin such operation. The resulting energization of the reverse motor control circuit causes the crank 11 to rotate in a clockwise direction. During approximately the initial 40 degrees of rotation of the crank 11, which may be defined as the first or unlocking portion of rotation, the roller 11b engages the arcuate slot 12a and causes the slide bar 12 to move toward the right, as viewed in FIG. 3, to an extent sufficient to disengage or withdraw the locking dog 12:: from the notch 9a, thus unlocking the switch points. During this initial rotation of the crank, the switch operating bar 8 does not experience any movement since the cam slot 8a is of such curvature to permit the free movement of the roller without engagement therewith. Accordingly, during this first part of movement of rotation of the crank 11, the slide bar 12 is shifted to its extreme right-hand position to unlock the switch points, but the switch operating bar 8 and, in turn, the switch points remain stationary. Simultaneously, the wedge-shaped cam 12d follows the unlocking movement of the slide bar 12 and forces the rollers 81a and 81b which engage the respective surfaces of the cam, and, in turn, the cam followers a and 80b apart. This separating action causes cam follower 80a to rotate bell crank 75a in a clockwise direction and causes cam follower 89b to rotate bell crank 75]) in a counterclockwise direction. The counterclockwise rotation of bell crank 75b does not materially effect its mechanical linkage or associated contact block but merely results in an angular disposition of the bell crank along with kicker arm 76b both of which are securely fixed to pivot shaft 72b. However, the clockwise rotation of bell crank 75a not only causes angular disposition of kicker arm 76a but also results in substantially changing the relative position of its linkage and its associated contact assembly. Since the adjusting stud 77a of kicker arm 76a is in communication with stop pin 71a of bell crank 70a, the angular rotation of the kicker arm 76a causes a proportional angular displacement of the bell crank 70a. The angular rotation of bell crank 70a causes the operating rod 73a and, in turn, the movable contact block 53a to move to its opposite position so that the normal indication contacts 45-48 are interrupted while the reverse motor control contacts 35- 38 and the shunt indication contacts 39 and 40 are closed. At the same time, the angular disposition of hell crank 70a is transmitted through the turnbuckle linkage to the crank 61a. The transmitted motion causes crank 61a to rotate in a counterclockwise direction which is effective in moving roller 63a away from recess 10a of the point detector bar and also in retracting pin 64a from notch of the lock rod. Accordingly, the circuit controller, and specifically contact assembly and mechanical coupling assemblage assume a mid-stroke position as is illustrated in FIG. 4.

However, as the crank 11 continues to rotate in a clockwise direction, the roller 11b engages the side of cam 8a of the switch operating bar 8 and begins to move the switch operating bar 8 downwardly, as viewed in FIG. 4. The resulting movement of the operating bar 8 causes the switch points to move in the same direction, namely, toward their reverse position. During this period of rotation of the crank 11, the slide bar 12 experiences substantially no movement since the roller 11b follows the curvature or contour of the arcuate slot 12a so that the circuit controller remains in the mid-stroke position as illustrated in FIG. 4. However, the movement of the operating bar 8 and, in turn, the switch points results in the movement of the lock bar 9 and the point detector bar 10 as is readily obvious from inspection of FIG. 4. This movement of the operating bar 8 continues for approximately degrees of rotation of the crank 1.1 at the end of which the switch points assume their proper reverse position, namely, switch point 2b engages fixed rail 11).

Upon completion of the switch point movement, the locking stroke or portion of the switch operation commences. The locking stroke involves approximately the final 40 degrees of rotation of the crank 11 and begins with the disengagement of cam slot 8a by the roller 11b and the engagement of cam slot 12a by the roller 1111. Since the roller 11b no longer engages the cam slot 8a, no further movement is imparted to the switch operating bar 8, however, the engagement of the roller 11b with the arcuate cam slot 12a causes the slide bar 12 to move toward its left-hand position. With the lock rod 9 properly positioned, the retraction of slide bar 12 causes the locking dog 122 to enter notch 9b of the lock rod thereby positively locking the switch points in their reverse position. The movement of the slide bar 12 also causes the retraction of the wedge-shaped cam 12d so that the rollers 81a and 81b along with their cam followers 80a and 80b are released and upon completion of the locking stroke the rollers 81a and 81b engage the small portion of the wedge-shaped cam member 12d. The releasing of the cam followers 80a and 80b permits the return of bell crank 75a and 75b and their associated kicker arms 76a and 76b by springs 78a and 78b, respectively. The counterclockwise rotation of the kicker arm 76a allows the pin 71a to be disengaged from the stud 77a, and the clockwise rotation of the kicker arm 76b permits the stop pin 71b to be disengaged from the stud 77d thereby permitting free movement of the two linkages. In viewing FIG. 5, it is readily noted that with the switch points properly positioned and locked as indicated by the disposition of the point detector bar and the lock rod, the crank 61b is permitted to rotate in a counterclockwise direction thereby causing the roller 63b to abut the recess a and causing the locking pin 64b to enter notch 9d. This rotational movement of the crank 61b is transmitted through the turnbuckle linkage to the bell crank 70b so that this bell crank is rotated in a clockwise direction. The angular rotation of hell crank 70b causes the operating rod 73b and, in turn, the movable contact block 58b to move to its opposite position so that the shunt indication contacts 29 and 30 and the normal motor control contacts 31-34 are opened and the reverse indication contacts 4144 are closed, as illustrated in FIG. 5. While the mechanical linkage associated with contact block 58a is free to move due to the disengagement of stud 77a from pin 71a no appreciable movement occurs since the roller 63a is disposed adjacent the larger diametrical portion of point detector bar 10 and the locking pin 64a is in engagement with the inner extremity of the lock rod 9. Accordingly, the contact block 58a remains in its present position wherein the normal motor control contacts 35-38 and the shunt indication contacts 39 and 40 are closed, and the normal indication contacts 45-48 remain opened. As is evident from the foregoing description, it is not possible for the reverse indication contacts to be closed thereby representing a clear signal to traffic until the switch points have been properly moved to their extreme position and have been positively locked therein. If for any reason the switch machine fails to complete its stroke, the contact blocks are in their left-hand extreme position corresponding to the mid-stroke position of the switch machine as shown in FIG. 4 so that a clear indication signal is incapable of being produced.

It is readily evident that in order to restore the switch points to their normal position from the reverse position, it is simply necessary to energize the normal motor control circuit. The crank 11 now begins to rotate in a counterclockwise direction and causes substantially the same sequence of operation, namely, unlock, operate, and lock, as described above. The entire operation is substantially the reverse as above described but with the exception that movable block 58b is moved rather than movable block 58a in order to initially interrupt the reverse indication contacts 41-44.

As previously mentioned, the point detector bar 10 is used not only to check the positive closure of the switch points during normal switch operation but also to detect damage to a switch point caused by dragging equipment or by trafi'ic running through the switch improperly while the railway switch is locked in either of its extreme positions. During normal operation, the indication contacts are positively opened by the wedge-shaped cam 12d of the slide bar 12 coacting with the cam followers 80a and 80b of the circuit controller coupling and are permitted to close at the termination of the switch locking stroke 12 when and only when the point detector bar and the lock rod are properly aligned.

First, let us explain the operation of the circuit controller and the point detector bar and particularly the manner in which they cooperate when the switch is trailed in its normal or reverse position. Assuming the switch is in the normal position as illustrated in FIG. 2, the trailing of the switch would cause separation of the switch point 2a from the fixed rail 1a thereby causing a downward displacement of the point detector bar 10. This downward displacement of the point detector bar causes roller 63a to move from recess 10d to the larger peripheral portion of the point detector bar thereby resulting in the rotation of the crank 61a about its pivoted shaft. The rotation of crank 61a is transmitted through the turnbuckle link to hell crank a thereby causing counterclockwise rotation of the bell crank 70a about its pivoted shaft. This counterclockwise rotation of hell crank 70a is transmitted through the operating rod 73a to the movable block 58a which interrupts the normal indication contacts 45-48. As a result, the control signals governing traffic over the switch will be a stop signal which will remain until an authorized maintainer repairs, adjusts and properly repositions the switch points for normal operation. A similar operation occurs when the switch is trailed in a reverse position with the exception that the roller 63b is effective in opening the reverse signal indication contacts 41-44 for producing a stop signal governing tratfic over the railway switch.

As previously mentioned, the point detector bar cooperates with the circuit controller to also constantly check against a misaligned, a broken and/or a bent point detector bar.

Let us assume that the point detector rod 10 is detached from the front rod 6, and that it is now desirable to move the railway switch from its normal position to its reverse position. The switch machine operates in its normal manner with the exception that no motion is imparted to the point detector bar since it is disconnected from the switch points. Upon completion of the switch operation, the switch points assume their reverse position, that is, the switch operating rod 8, the slide bar 12, and the lock rod 9 assume a position as shown in FIG. 5. However, since the roller 63b of the crank 61b remains engaged with the larger diametrical or peripheral portion of the point detector bar 10 the lock pin 64b is prevented from entering the recess 9d so that the movable block 58b is prevented from being moved, and the reverse indication contacts 41- 44 remain opened. Further, since the lock pin 64a engages the inner extremity of lock rod 9 the normal indication contacts 45-48 are incapable of being closed. Accordingly, with neither of the indication contacts closed, a stop signal is produced which prevents the flow of traflic over the railway switch. Should the point detector bar 10 become detached from the front rod 6 when the railway switch is in its reverse position, the roller 63a and the lock pin 64b would cooperate to maintain the normal and reverse indication contacts opened so that a stop signal would be generated and prevent traflic flow over the switch.

A misaligned or bent point detector rod 10 would normally cause both of the rollers 63a and 63b to continually engage the larger diametrical portion of the point detector rod so that closure of the normal and reverse indication contacts would be prevented thereby promptly alerting authorized personnel that the railway switch requires maintamence. It should be noted that in each of the above circumstances, the shunt indication contacts 2930 and 3940 are closed so that an added measure of safety is presented in that stray currents or crosses 0n the external wires1 are incapable of producing a false indication clear signa Further, as mentioned above, the circuit controller also ensures that the switch points must be properly locked in the extreme position to which they have been moved prior to permitting a clear signal to be produced. For instance if the lock rod 9 is accidentally disconnected or broken away from the front rod 6, the circuit controller will function to produce a stop signal thereby preventing the movement of traffic over the switch. For example, let us assume that while the switch machine occupies its normal position as illustrated in FIG. 2, the lock rod '9 has become inadvertently disconnected from the switch points. Now when the switch machine is operated for movement to its reverse position, the detached lock rod 9 obviously remains in its normal position as shown in FIG. 2, however, the switch operating bar 8 and the slide bar 12 move and complete the switch operating cycle and assume their usual reverse position as shown in FIG. 5. Similarly, the point detector bar is moved by the switch points to its reverse position and assumes the position as shown in FIG. 5. The reversal of the switch points to their reverse position causes the movable block 58a to shift positions in the usual manner so that normal indication contacts 45-48 become open while the normal motor control contacts 3538 and shunt indication contacts 3940 become closed through the interaction of the wedge-shaped cam 12d and the cam follower 80a. Upon completion of the operating stroke, the roller 63a is situated adjacent the larger peripheral portion of the point detector bar so that rotation of the crank 61a is prohibited, even though the lock pin remains adjacent the upper locking notch 90. However, the roller 63b is now positioned adjacent the recess 10a but rotation of the crank 61b is prevented by the lock pin 64]) engaging the outer extremity of the lock rod 9. Accordingly, no return movement is imparted to either movable block 580 or 58b and the electrical contacts remain in the position as shown in FIG. 4 thereby preventing a clear signal from being produced.

In the event that the lock bar 9 should become disconnected when the switch machine is in its reverse position, the transposition of the switch points will open all the indication contacts and will close all the motor control and shunt indication contacts. Upon the completion of the operating stroke the engagement of roller 63b with the larger peripheral portion of the point detector bar 10 and engagement of the lock pin 64a with the inner extremity of the lock rod 9 will prevent the closure of any of the indication contacts. Accordingly, the operation of the railway switch from a remote point during lock rod failure will cause a continuous failure of the signals to clear when the switch is moved into an extreme position thereby indicating that the switch is not functioning properly and requires the attention of a maintainer.

Thus, we have disclosed not only a railway switch machine which operates with a high degree of efiiciency and reliability but also an improved circuit controller which functions to readily detect failure so that the highest degree of safety to persons and equipment is ensured.

Further, during routine inspection or required maintainance periods, the general condition of the circuit controller and, particularly, the position of the electrical contacts in relation to the switch points may be readily and visibly ascertained and, if necessary, may be promptly corrected and repaired due to the adroit disposition of the various elements.

In addition, the utilized circuit controller facilitates not only the replacement of elements in the field but also the ambidexterity of assembly in the factory.

Although we have herein illustrated and described only one form of the apparatus embodying our invention, it is understood that various changes and modifications may be made therewith within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. A circuit controller for a railway switch machine which performs a positioning and a locking correspondence check for ensuring that the switch points are properly positioned and locked in the extreme position to which they have been moved prior to initiating closure of selected electrical contacts, comprising a point detector bar having a recess, a lock rod having a pair of upper and a pair of lower notches, said point detector bar and said lock rod suitably connected to the switch points to move therewith, a slide bar having a locking dog engaging one of said pair of lower notches for locking the switch points in their first extreme position and engaging the other of said pair of lower notches for locking the switch points in their second extreme position, a mechanical coupling assemblage including a first and a second linkage, an electrical contact assembly including a first and a second group of fixed contacts and a first and a second group of movable contacts, said first group of movable contacts connected to said first linkage, said second group of movable contacts connected to said second linkage, said first linkage including a first crank having a roller and a pin which simultaneously com municate with the recess of said point detector bar and one of said pair of upper notches of said lock rod when and only when the switch points are properly positioned and locked in their first extreme position to initiate the closure of selected fixed contacts of said first group by movable contacts of said first group, and said second linkage including a second crank having a roller and a pin which simultaneously communicate with the recess of said point detector bar and the other of said pair of upper notches of said lock rod when and only when the switch points are properly positioned and locked in their second extreme position to initiate the closure of selected fixed contacts of said second group by movable contacts of said second group.

2. A circuit controller as defined in claim 1 wherein said selected fixed contacts of said first group comprise a plurality of spring-type contacts for the reverse indication circuit, and said selected fixed contacts of said second group comprise a plurality of spring-type contacts for the normal indication circuit.

3. A circuit controller as defined in claim 1, wherein said first and second linkages each include a turnbuckle link, a bell crank, and a push rod suitably interconnected between said first and second groups of movable contacts and said first and second cranks.

4. A circuit controller as defined in claim 2, wherein said first group of movable contacts comprise a plurality of knife-blade contacts for bridging selected pairs of said plurality of spring-type contacts of said first group of fixed contacts, and said second group of movable contacts comprise a plurality of knifeblade contacts for bridging selected pairs of said plurality of said second group of fixed contacts.

5. A circuit controller for use in a railway switch machine of the type which experiences an unlocking, an operating, and a locking stroke in moving the switch points between their two extreme positions comprising, a point detector bar having a recess, a lock rod having a pair of upper and a pair of lower notches, said point detector bar and said lock rod suitably connected to the switch points to move therewith, a slide bar having a locking dog engaging one of said pair of lower notches for locking the switch points in their first extreme position and engaging the other of said pair of lower notches for locking the switch points in their second extreme position, said slide bar having a wedge-shaped cam, a mechanical coupling assemblage including a first and a second linkage, an electrical contact assembly including a first and a second group of fixed contacts and a first and a second group of movable contacts, said first group of movable contacts connected to said first linkage, said second group of movable contacts connected to said second linkage, said first linkage including a cam follower cooperating with said wedge-shaped cam to initiate the opening of selected fixed contacts of said first group by the movable contacts of said first group and including a first crank having a roller and a pin which simultaneously communicate with the recess of said point detector bar and one of said pair of upper notches of said lock rod when and only when the switch points are properly positioned and locked in their first extreme position to effect the closure of the selected fixed contacts of said first group by the movable contacts of said first group, and said second linkage including a cam follower cooperating with said wedge-shaped cam to initiate the opening of selected fixed contacts of said second group by the movable contacts of said second group and include a second crank having a roller and a pin which simultaneously communicate with the recess of said point detector bar and the other of said pair of upper notches of said lock rod when and only when the switch points are properly positioned and locked in their second extreme position to effect the closure of selected fixed contacts of said second group by the movable contacts of said second group.

6. A circuit controller as defined in claim 5, wherein said first and second groups of selected fixed contacts comprise a plurality of U-shaped spring contacts.

7. A circuit controller as defined in claim 5, wherein said first and second groups of movable contacts comprise a plurality of knife-blade bridging contacts.

8. A circuit controller as defined in claim 5, wherein said first and second groups of selected fixed contacts comprise the indication contacts of the railway switch machine.

9. A circuit controller as defined in claim 5, wherein said first and second linkages each include a turnbuckle a first bell crank, and a push rod suitably interconnected between said first and second groups of movable contacts and said first and second cranks for initiating the closure of the selected fixed contacts of said first and second groups.

10. A circuit controller as defined in claim 9, wherein said first and second linkages each include a second bell crank and a kicker arm cooperatively associated with the cam follower and the first bell crank of the first and second linkages to effect the opening of the selected fixed contacts of said first and second groups.

11. A circuit controller for use in a railway switch machine of the type which performs an initial unlocking of the switch points, an intermediate moving of the switch points between two extreme positions, and a final locking of the switch points, comprising a point detector bar having a reduced portion, a lock rod having a first and a second pair of notches, said point detector bar and said lock rod suitably secured to the switch points and movable therewith, a slide bar having a locking dog and a cam member, said locking dog engaging one of said first pair of notches for locking said switch points in one extreme position and engaging the other of said first pair of notches for locking said switch points in the other extreme position, a first and a second group of fixed contacts and a first and a second group of movable contacts electrically associated therewith, a first mechanical linkage suitably connected to said first group of movable contacts and having a cam follower cooperatively associated with said cam member for electrically interrupting a first selected set of fixed contacts and closing a second selected set of fixed contacts of said first group by said first group of movable contacts when the switch points are initially unlocked from their first extreme position, a second mechanical linkage suitably connected to said second group of movable contacts and having a crank with a roller and a pin cooperatively associated with the reduced portion of said point detector bar and one of said second pair of notches of said lock rod for electrically interrupting a second selected set of fixed contacts and closing a first selected set of fixed contacts of said second group by said second group of movable contacts when the switch points are properly positioned and are finally locked in their second extreme position, said second mechanical linkage having a cam follower cooperatively associated with said cam member for electrically interrupting said first set of fixed contacts and closing said second set of fixed contacts of said second group by said second group of movable contacts when the switch points are initially unlocked from their second extreme position, and said first mechanical linkage having a crank with a roller, and a pin cooperatively associated with the reduced portion of said point detector bar and the other .of said second bar of notches of said lock rod for electrically interrupting said second set of fixed contacts and closing said first set of fixed contacts of said first group by said first group of movable contacts when the switch points are properly positioned and are finally locked in their first extreme position.

12. A circuit controller as defined in claim 11, wherein said first and second groups of fixed contacts are U-shaped spring contacts. 7

13. A circuit controller as defined in claim 11, wherein said first and second groups of movable contacts are knife-blade bridging contacts.

14. A circuit controller as defined in claim 11, wherein said first set .of fixed contacts of said first and second groups are the signal indication contacts and said second set of fixed contacts of said first and second groups are the motor control and shunt contacts for the railway switch machine.

15. A circuit controller as defined in claim 11, wherein said first and second mechanical linkages each include a turnbuckle link, a first bell crank, and a push rod suitably interconnected between said first and second groups of movable contacts and the cranks of said first and second linkages for interrupting said second selected sets of fixed contacts of said first and second groups and for closing said first selected sets of fixed contacts of said first and second groups.

16. A circuit controller as defined in claim 11, wherein said first and second mechanical linkages include a second bell crank and a kicker arm cooperatively associated with the cam followers and the first bell crank of said first and second linkages for interrupting the first set of fixed contacts of said first and second groups and for closing the second set of fixed contacts of said first and second groups by said first and second groups of movable contacts.

17. A circuit controller as defined in claim 11, wherein said first and second mechanical linkages each include a first spring connected to the cranks of said first and second linkages for constantly urging their rollers toward said point detector bar and their pins toward said lock bar.

18. A circuit controller as defined in claim 16, wherein said first and second mechanical linkages each include a second spring connected to the second bell cranks of said first and second linkages for constantly urging their cam followers toward said cam member. 1

19. In a railway switch machine having a casing, a point detector bar provided with a recess and suitably mounted within the casing for movement between a first and a second extreme position, a lock rod provided with a first and a second pair of notches and suitably mounted within the casing for movement between a first and a second extreme position, a slide bar suitably mounted within said casing for longitudinal movement therein and provided with a locking dog for engaging one of said first pair of notches when said lock rod occupies its first extreme position and for engaging the other of said first pair of notches when the lock rod occupies its second extreme position, a first and a second pivoted crank each provided with a roller and a pin, a first spring connected to said first pivoted crank for suitably biasing the roller of said first pivoted crank in engagement with the recess of said point detector bar and the pin of said first pivoted crank in engagement with one of said second pair of notches of said lock rod when and only when said point detector bar and said lock rod occupy their first extreme position, a second spring connected to said second pivoted crank for suitably biasing the roller of said second pivoted crank in engagement with the re- 17 cess of said point detector bar and the pin of said second pivoted crank in engagement with the other of said second pair of notches of said lock rod when and only when said point detector bar and said lock rod occupy their second extreme position, a first and a second pivoted bell crank each provided with a push rod for controlling the electrical condition of a first and a second group of contacts, a first adjustable means interconnecting said first pivoted crank with said first pivoted bell crank, a second adjustable means interconnecting said second pivoted crank with said second pivoted bell crank, a wedgeshaped cam member mounted on said slide bar, a first and a second cam follower each provided with a roller, a third pivoted bell crank connected to said first cam follower, a fourth pivoted bell crank connected to said second cam follower, a third spring connected to said third pivoted bell crank for suitably biasing the roller of said first cam follower in cooperative engagement with said wedge-shaped cam member, a fourth spring connected with said fourth pivoted bell crank for suitably biasing the roller of said second cam follower in cooperative engagement with said wedge-shaped cam memher, a first kicker arm pivotally connected with said third pivoted hell crank and provided with a stud which is adapted to engage and rotate said first pivoted bell crank whereby said first group of electrical contacts is interrupted when the locking dog of said slide bar is withdrawn from said one of said first pair of notches of said lock rod, and a second kicker arm pivotally connected with said fourth pivoted bell crank and provided with a stud which is adapted to engage and rotate said second pivoted bell crank whereby said second group of electrical contacts is interrupted when the locking dog of said slide bar is withdrawn from said other of said first pair of notches of said lock rod.

References Cited UNITED STATES PATENTS 2,64l,69l 6/1953 Bone 246253 2,651,714 9/1953 Poole 246263 2,786,939 3/1957 Bone 246-253 ARTHUR L. LA POINT, Primary Examiner.

D. F. WORTH, Assistant Examiner. 

